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The present contribution highlights results of the recent irradiation campaigns applied to screen mechanical properties of advanced tungsten and copper-based materials—main candidates for the application in the plasma-facing components (PFC) in the European DEMO, which has also been presented at 28th IAEA fusion energy conference. The main challenges in the formulated irradiation programme were linked to: (I) assessment of the ductile-to-brittle transition temperature of newly developed tungsten-based materials; (ii) investigation of an industrial pure tungsten grade under high temperature irradiation, reflecting operational conditions in the high flux divertor region; (iii) assessment of the high temperature strength of CuCrZr-based alloys and composites developed to enable the extension of the operational window for the heat sink materials. The development and choice of the advanced materials is driven naturally by the need to extend the operation temperature/fluence window thereby enlarging the design space for PFCs. The obtained results helped identifying the prospective tungsten and copper-based material grades as well as yielded a number of unexpected results pointing at severe degradation of the mechanical properties due to the irradiation. The results are discussed along with the highlights of the microstructural examination. An outlook for near future investigations involving in-depth post-irradiation examination and further irradiation campaigns is provided.

In the current work we use the failure assessment diagram (R6) to deduce ductile fracture toughness for the reduced activation ferritic/martensitic steel EUROFER97 by applying Small Specimen Testing Technology. Fracture parameters have been determined in quasi-static three-point-bend experiments. The fracture toughness results obtained with option 1 curve of R6 are sensibly independent of specimen geometry, constraint state and initial crack length and agree well with the results obtained by the analysis of crack resistance curves. Application of option 2 curve of R6 results into less conservative fracture toughness values.

In blankets of a fusion power plant 14 MeV neutrons produce displacement damage, dpa, and helium and hydrogen. Martensitic steels offer the advantages of low swelling and reduced helium embrittlement compared to austenitic steels. Reduced activation Eurofer 97 steel has been exposed to neutron displacement damage up to about 15 dpa in materials test reactors such as OSIRIS and HFR at temperatures in the range of RT to 600 °C, and up to 80 dpa in BOR-60 at temperatures in the range of 300–330 °C. The post-irradiation mechanical properties in the range of 300–330 °C show increases in yield stress, decrease in ductility and an increasing ductile to brittle transition temperature. The hardening rate is decreasing with increasing damage level, but it does not show saturation at doses examined. Analyzing the present results and reviewing properties of other steels with different compositions, including ODS steels, lead to the conclusion that improvement of the radiation resistance of steel will be based on nano-microstructural features.

HgBa 2 CaCu 2 O 6 + δ thin films were prepared on lanthanum aluminate (LaAlO 3 ) as well as on CeO 2 buffered r -plane sapphire substrates through a conversion process using Tl 2 Ba 2 CaCu 2 O 8 + δ films as well as thallium free amorphous Ba–Ca–Cu–O films as precursors. The c -axis oriented HgBa 2 CaCu 2 O 6 + δ films show high critical current densities at 77 K: above 8 MA/cm 2 on LaAlO 3 and 6 MA/cm 2 on buffered sapphire. Using the dielectric resonator technique the microwave surface resistance R s was determined to be below 1 and 3.2 mΩ, at low fields and at 77 K and 17.8 GHz, for films on LaAlO 3 and buffered sapphire, respectively. However, several films show strong increases of R s with field amplitudes B HF > 1 mT and even higher low field R s values of above 10 mΩ, which are remarkable higher than expected for high quality HgBa 2 CaCu 2 O 6 + δ or Tl 2 Ba 2 CaCu 2 O 8 + δ and YBa 2 Cu 3 O 7 − δ thin films. We present R s measurements of HgBa 2 CaCu 2 O 6 + δ films on both substrate materials and discuss possible defects and degradation mechanisms. The layer growth process, which includes melting phenomena instead of only cation-exchange of Tl with Hg, will be discussed. We consider the thallium to play a key role for the conversion process.

Oxygen doping enhancing the CuO plane density of states nm is well known to improve normal conducting and superconducting dc, ac and rf transport properties of Y Ba2Cu3O7−δ (YBCO) by orders of magnitude. By Ca doping Y1−xCaxBa2Cu3O7−δ, enhancing nm similarly, transport improvements by factors between two and ten have been found for bicrystal junctions and single crystals only. To study the effect of Ca doping on epitaxial pulsed laser deposition (PLD) films on CeO2/Al2O3 we performed systematic transport studies for nominal x = 0, 0.1, 0.15 and 0.2 combined with energy dispersive x-ray (EDX) and Rutherford back-scattering (RBS) analysis. The resulting superconducting rf properties, and therewith the mean values of the weak link critical current density jcJ, degraded with Ca content, confirming trends found by dc measurements of PLD films on SrTiO3 (STO) and on LaAlO3 (LAO) and by rf measurements of Ca-doped films on CeO2 buffered Al2O3 (AO) and on LAO. The normal conducting weak link resistance Rbn decreased with x in line with nm enhancements but jcJRbn also decreased. Reasons for the jcJ and jcJRbn degradations and the morphology changes and for the differences between Ca-doped YBCO bicrystal junctions and natural junctions in Ca-doped epitaxial YBCO films will be given.

Radio-frequency (rf) superconducting devices are very sensitive to corrosion because of the small penetration depths λ

Ca doping of YBa 2 Cu 3 O 7− δ (YBCO) is well known to enhance the critical current density in large-angle grain boundaries for example of bicrystals. However, up to now no data are available on microwave properties of epitaxial Ca-doped YBa 2 Cu 3 O 7− δ thin films on r -plane sapphire with CeO 2 buffer layer. Therefore, first results are presented for large-area pulsed laser deposition (PLD) grown Ca x Y 1− x Ba 2 Cu 3 O 7− δ films on 3-in. diameter sapphire wafers. The PLD process is optimised for undoped YBCO thin films and shows high reproducibility for YBCO. The microwave surface resistance R s at 8.5 GHz of Ca-doped YBCO ( x =0.1) thin films shows clear reduction (up to 20%) with respect to that of YBCO for temperatures from about 20–50 K. In addition, microwave surface resistance R s of Ca-doped YBCO is lower than that of YBCO even for enhanced microwave surface magnetic field up to about 20 mT for temperatures 20 and 40 K.

The local surface modification as well as the direct micro-ablation of polymethylmethacrylate (PMMA) with UV-laser radiation was studied with respect to the fabrication of optical monomode waveguides. Different UV sources were applied with a focus on excimer lasers and frequency-multiplied Nd:YAG lasers to investigate several concepts of integrated waveguides. One type of waveguides is realized by localized physical modification, which leads in one step to an integrated polymer waveguide with higher refractive index. A complementary type of waveguides includes the formation of small grooves, which are filled with index matched materials introducing a micro-scaled increase or decrease of the refractive index into the original PMMA substrate. The different laser-assisted fabrication techniques for polymer waveguide formation as well as the characterization of their local optical properties are discussed in detail. Lasergestutzte Fertigung von monomodigen Wellenleitern in Polymeren und ihre optische Charakterisierung Grundlegende Untersuchungen mittels UV-Laserstrahlquellen zur Fertigung von monomodigen optischen Wellenleiterstrukturen in Polymethylmetacrylat (PMMA) wurden durchgefuhrt. Hierzu wurden Prozesse zur lokalen Materialmodifizierung sowie ein Verfahren unter Einsatz von Mikroformabtrag studiert und weiterentwickelt. Fur die Arbeiten wurden Excimer-Laser (Wellenlangen: 193 nm, 248 nm), frequenzvervierfachte Nd:YAG-Laser (266 nm) und erganzend eine breitbandige UV-Lampe verwendet. Eine Sorte wellenleitender Strukturen basiert auf einer lokalen Brechungzahlerhohung mittels physikalischer Modifizierung, hier ermoglicht Laserstrahlung im Vergleich zur Maskenbelichtung mit UV-Lampen zusatzlich eine direkt schreibende Prozessfuhrung. Die zweite Fertigungsmethode setzt sich aus einer Abfolge von lasergestutztem Mikroformabtrag, mit dem Kanalstrukturen in PMMA erzeugt wurden, und einer Befullung mit brechzahlangpasstem Material zusammen, wodurch auf Mikrometerskalen der Brechungsindex lokal auf dem PMMA Substrat erhoht oder abgesenkt werden konnte. Die Diskussion der unterschiedlichen lasergestutzten Fertigungstechniken zur Herstellung polymerer Wellenleiterstrukturen wird in diesem Beitrag gefuhrt in Verbindung mit der Charakterisierung der lokalen optischen Eigenschaften.

YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) film quality has reached a stage enabling rf applications at T/spl les/80 K. Higher operating temperatures or better power handling are very much desired. Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub 8/ (Tl-2212) is a perfect candidate with its higher transition temperature T/sub c/>100 K. We studied the rf field dependence of the impedance Z/sub s/ of epitaxial Tl-2212, which shows already surface resistances at low fields superior to YBCO and promising power handling with a nonlinearity onset above /spl mu//sub 0/H/sup *//spl sime/3 mT. Defective Tl-2212 films show anomalous nonlinear behavior for /spl mu//sub 0/H/sub rf//spl les//spl mu//sub 0/H/sup *//spl sim/0.3 to 1 mT, extremely pronounced at T

The application of HTS is obstructed by high surface impedances and their increases Z(T,f,H/sub rf/) with rf field. To separate intrinsic from extrinsic and rf mode from HTS material properties well characterized films are required. Using TBCCO films and corrosion protected YBCO films well defined material and physical parameter dependencies have been found which for the first time allowed a unique separation of intrinsic surface resistances R/sub int/(T,f,H/sub rf/) from extrinsic residual losses R/sub res/(T,f,H/sub rf/) and shed light onto /spl delta/Z/spl prop/H/sub rf//sup 2/ increases observed in TE/sub 011/ modes. The latter confirms that rf results of TE/sub 01n/-mode end-plate replacements are sensitive tools to study HTS thin film material properties before structuring. Aside from /spl delta/R/sub s/(H/sub rf/)/spl prop/H/sub rf//sup n//spl prop//spl delta/X/sub s/(H/sub rf/), rf measurements in the frequency and time domain yield the ratio r=/spl delta//sub s///spl delta//sub s/ which shows distinct T and f dependencies for various mechanisms and rf modes. r(T,f)/spl ap/1 indicates hysteresis losses of Josephson fluxons governed by the weakest links at the edges of the films, being weighted differently in TE/sub 01n/ and strip-line modes.

We study the rf field dependence of Z s of epitaxial large area (2–3 inch) YBa 2 Cu 3 O 7 and Tl 2 Ba 2 CaCu 2 O 8 films using a dielectric resonator with TE 011 @8.5 GHz at 4.2 T H rf ⩽10 mT. The lateral R s -homogeneity of the films were analyzed with an open resonator at 145 GHz. Some Tl 2 Ba 2 CaCu 2 O 8 films shows anomalous nonlinear behavior extremely pronounced at T μ 0 H rf ⩽0.3 mT indicating the presence of very weak-links saturating already at low rf currents. At μ 0 H rf >0.3 mT the rf field dependence of all Tl 2 Ba 2 CaCu 2 O 8 films can be described by δ R s ( H rf )∝ H rf n ∝δ X s ( H rf ). The observed exponents n ≈1–2, together with the ratios r =δ X s /δ R s ∼1 hint to Josephson fluxons in weak-links.

High quality double-sided YBCO wafers with ceria buffered sapphire substrates are analysed for the lateral homogeneity and field dependence of the surface resistance (RS) using an open resonator at 145 GHz and a dielectric resonator at 8.5 GHz. In a following step, a set of linear microstrip resonators are patterned on these wafers and are analysed for their high frequency performance at 4 GHz. The results reveal surface resistance analysis of YBCO wafers as a reliable basis for materials qualification. At low power levels the high Q-factors of the microstrip resonators (about 30 000) are consistent with the measured RS-values at the considerably higher frequencies. Further the power handling capabilities of the resonators agree with the measured field dependence of RS. Surface resistance mappings at 145 GHz effectively indicates critical film areas for non-optimum microstrip resonator performance.

Epitaxially grown large area YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films are promising for the application in passive microwave devices (e.g. resonators, filters, antennas). The main criteria for these applications are low microwave losses and good power handling capabilities of the devices. Various measurement techniques are in use for the evaluation of the power handling capabilities of YBCO thin films. However, only few studies exist relating their results to the actual performance of the microwave devices. We investigate the rf field dependence of the surface resistance of YBCO thin films using a dielectric resonator technique at 8.5 GHz and 77 K. The lateral homogeneity of the films with respect to the surface resistance is analyzed with an open resonator technique at 145 GHz and 77 K. Subsequently the films are patterned to microstrip resonators and their quality factors are measured at 4 GHz and 77 K as a function of the input rf power. The results show that the low values of the surface resistance and its constant level up to high rf magnetic fields /spl sim/10 mT are necessary requirements but not stringent criteria for good power handling capability of the microstrip resonators.

The application of HTS is obstructed by the nonlinear behavior of Z(T,f,H/sub rf/) with rf field. The study of those nonlinearities profits by carefully calibrated rf measurements in the frequency and time domain, which yield /spl delta/R/sub S/(H)/spl prop/H/sup n//spl prop//sub S/(H). In contrast to /spl delta/R/sub S/(H)/spl prop/H/sup n/, the ratio r=/spl delta/X/sub S///spl delta/R/sub S/ is independent of geometry factor and shows distinct T and f dependencies for various mechanisms and rf set-ups. The high power rf response in the frequency domain yields nonlinear resonance curves, n and r values. The time domain measurements give useful insight about dynamics of the underlying nonlinear mechanisms. The results r/spl ap/1 and n/spl ap/1-2 are in line with Josephson fluxons in weak links, which may interact with dc fluxons threading through the weak links.

Epitaxially grown large area YBCO films are essential for superconducting high frequency devices, e.g. microstrip filters for telecommunications. Therefore, c-axis oriented, 250 to 500 nm thick YBCO films were simultaneously deposited by sputtering from hollow cylindrical targets on both sides of CeO/sub 2/ buffered 3" sapphire wafers. The lateral homogeneity was analyzed by mapping the surface resistance, R/sub s/, at 145 GHz and 75 K. Values of R/sub s/ below 50 m/spl Omega/ were reached over the whole area. The HF power handling capability was demonstrated by a break down field higher than 10 mT at 8.5 GHz and 77 K. In order to demonstrate the quality of our sputtered films with respect to large area high frequency applications, simple microstrip resonators were patterned by UV photo lithography and wet chemical etching. At a circulating power of up to 1 W, very high unloaded quality factors, Q/sub 0/, of up to 32000 at 4 GHz and 77 K were achieved. Above 5 W, Q/sub 0/ decreased due to the field dependence of R/sub s/. The operation of complex structures was demonstrated by 3 pole and 7 pole bandpass filters operated at 77 K and 2 GHz and 6 GHz, respectively. The filters, tuned by brass tuning elements, showed transmission losses of less than -0.3 dB and reflection losses of more than -17 dB.

With the vibrating reed technique we have studied the magnetoelastic behavior and the dynamical response of amorphous and crystalline magnets in the ferromagnetic and re-entrant spin glass states. The measurements have been performed as a function of magnetic field, temperature and angle between the sample’s main area and the applied field. The resonance frequency of the reed is influenced by a static contribution (pole effect), a dynamic contribution with a large effect due to the pinning of magnetic domains and magnetostrictive effects. When the field is applied perpendicular to the main area of the sample, a large decrease of the resonance frequency is observed which is rather independent of the material characteristics and is not related to a change of the Young modulus. A field misalignment of a few degrees strongly affects the field dependence of the resonance frequency. We briefly discuss the influence of the re-entrant spin glass state on the magnetoelastic behavior and the characteristics of the internal friction of vibrating ferromagnets in a magnetic field.

The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of the reed and the magnetomechanical pole effect within a domain rotation model and is not related to magnetoelasticity.

We measured the acoustic properties of amorphous thin $\mathrm{SiO}{}_{2}$ films with thickness $20\ensuremath{\le}t\ensuremath{\le}500\mathrm{nm}$ in the temperature range $0.1\mathrm{mK}\ensuremath{\le}\mathrm{T}\ensuremath{\le}1\mathrm{K}$ and at frequencies $\ensuremath{\nu}\ensuremath{\sim}10\mathrm{kHz}$. We found that the sound velocity maximum of these films is strongly affected by the film thickness. This unexpected behavior can be attributed to a modification of the phonon mediated interaction between tunneling systems due to the smaller dimensionality of the films, and supports recently published models on the nature of low-energy excitations in amorphous solids.

We have measured the sound velocity and attenuation of polycrystalline Cu, Al, Nb, Nb 48 Ti 52 , Pt, P 20 Rh 30 , Pt(l%W), Pd, Ta, NiCr alloy and amorphous PdSiCu at frequencies 0.1 kHz < v < 20 kHz and at temperatures 40 mK < T < 10K. All polycrystalline samples show acoustic properties which resemble those of dielectric glasses. Their electrical resistivity is in the range 10- 10 Ωm < p < 10 -5 Ωm with an estimated electron mean free path of 10- 10 m < l< 10 -5 m. Our results indicate no correlation between the tunneling system density of states or coupling constant and the electron mean free path, supporting earlier work on the absence of electron assisted relaxation rate. For polycrystalline metals we found that the ratio T∞ / v 1/3 (0.006 ± 0.002) K/Hz 1/3 in agreement with dielectric glasses (T∞ is the temperature at the sound velocity maximum).

We have investigated the relative change of the sound velocity of polycrystalline metals at frequencies 0.1 kHz ≤ ν ≤ 20 kHz and at temperatures 0.04 K ≤ T ≤ 10 K. For all metals investigated the relative change of the sound velocity decreases linearly with temperature above ~ 1 K. We show that the temperature coefficient β of this linear dependence is directly proportional to the slope C obtained from the logarithmic temperature dependence below 1 K. This result is in agreement with theoretical results recently proposed by Neu and Wurger based on a new relaxation mechanism for tunnelling systems. Moreover, we show that the universal behaviour between β and the elastic modulus recently found by Nava for amorphous solids also holds for polycrystalline metals and can be explained within the same model.

Different process technologies for the rapid fabrication of micro-fluidical and micro-optical components made of polymers will be presented. Single prototypes are generated by the direct patterning or modification of plastics with UV-laser radiation. For the fabrication of small and large series laser-assisted micromachining using neodymium:yttrium aluminum garnet (Nd:YAG) and excimer laser allows for a rapid manufacturing of microstructured polymeric and metallic mould inserts. Plastic replication like hot embossing, injection moulding or reaction injection moulding of the generated microstructured mould inserts gives access to mouldings carrying structural details in the micrometer range and/or high aspect ratio microstructures.

In the microscopic world the need of functional prototypes increases, e.g. as a precondition for a mould insert fabrication for micro-injection moulding. In this work the direct fabrication of prototypes made from polymers with an accuracy down to the micrometer range will be presented. For this purpose the direct patterning or modification of polymers with UV-laser radiation is performed for applications in fluidic and micro-optics. Different UV laser sources such as excimer and frequency-multiplied Nd:YAG were used. In the case of complex designs for fluidic applications it is powerful to use Nd:YAG laser radiation as patterning tool because of their high laser repetition rates: CAD data from complex fluidic designs were transmitted directly via CAM module into the polymeric surface. Because of the very small laser pulse duration of about 400-500 ps the thermal-induced damage during ablation decreases significantly. Process parameters, ablation rates and attainable surface qualities for capillary-electrophoreses chips will be presented. With the aid of a motorised aperture or a rotating mask system, excimer laser radiation is used to enable a well defined patterning of grooves with sharp edges and smooth sidewalls. The direct ablation of polymethylmethacrylate (PMMA), as well as the laser induced modification of the polymeric chemistry is used for the preparation of passive integrated-optical waveguides. Two types of concepts of waveguides are discussed: 1. Laser patterned grooves are filled with index matched materials which leads either to an increase or a decrease of the refractive index relative to pure PMMA. 2. Localised laser-induced polymer modification leads immediately to an integrated waveguide with higher refractive index. Both types of waveguides-concepts are characterised by their optical properties, which will be discussed in detail.

We have studied the magnetomechanical behavior of the amorphous metal METGLAS 2826A (Fe 32 Ni 36 CT 14 P 12 B 6 ) in the as-quenched and annealed states at temperatures 50mK